IDENTIFICATION OF A HUMAN CDNA HOMOLOG TO THE DROSOPHILA TRANSLOCATION PROTEIN-1 (DTRP1)

In yeast, several integral membrane proteins such as Sec61p, Sec62p an d Sec63p have been reported as the components involved in protein tran slocation across and into the endoplasmic reticulum (ER) membrane. Amo ng them, the homologues of Sec61p have been found both in bacterias an d mammals, whereas those of Sec62p or Sec63p have not. So, Sec61p seem to be the evolutionary conserved component, while Sec62p and Sec63p m ay not. To date, no homologues of Sec62p have been found in mammals ye t. Here, we report a novel human cDNA, HTP1 (for human translocation p rotein 1), that encodes a protein of 399 amino acids that is 36.3% ide ntical (64.6% similar) to Drosophila homologue of Sec62p, Drosophila t ranslocation protein 1 (Dtrp1). Northern blot analysis showed two HTP1 transcripts of about 2.8 and 5.5 kb, which were expressed concomitant ly in various human tissues such as heart, brain, placenta, liver and pancreas. (C) 1997 Academic Press